Question

What is an example of a homologous and a vestigial structure? How is this evidence for evolution?

Answer 1

Evolution is the change in the genetic makeup of the population over a period of time. Fossils, physical and molecular features, and geographic information act as evidence for evolution.

Complete answer:
According to Darwin in evolution species change and give rise to new species with modifications. The study of the comparative anatomy of these structures is evidence for evolution.
Homology is evidence of this theory as homology is the similarity in species due to the common descent.
Homologous structures are those which are similar in many species due to the common descent but will not necessarily have the same function. An example of this is the forelimbs in mammals like dogs, bats, whales, cats, and humans. All have a similar structure of bones in their forearms but do not look the same from outside.
The vestigial structures are the organs that do not have any function but were functional in the ancestors who had this structure. Evolution eliminated the need for these structures. An example is a tailbone in the human embryo which disappears as the development takes place and the tailbone gets fused with the vertebrae. The wisdom tooth is another example of vestigial organs in humans as the extra teeth were required by our ancestors to grind food but the need disappeared in modern man as they do not require the third molars.
This proves that the genes for controlling these characters are still present in the genotype but is partially or not expressed that this is also an evidence in support of evolution.
Note: Evolution is important to study as it tells how modern organisms evolved from ancient life forms and how they are changing. It is very important to not confuse the terms homologous and analogous organs.
1)Homologous organs can be defined as the organs of different animals that have a similar structure but differ in their functions.
2)Analogous organs can be defined as the organs of different animals that are structurally different but perform the same functions.